Power semiconductor devices are widely used as electrical power conversion devices in consumer electronics, industrial machines, motor vehicles and high-speed trains, etc. By means of the improvements on the structure, the improvements of the performance are achieved year by year. Compared with a planar device, a power device using groove technology provides a channel width with an obvious increase per unit area. In addition, a semiconductor device using groove technology provides an excellent switch characteristic and is used in applications having requirements for fast switching.
In accordance with United States patent application US2012/0104555A1, an IGBT having a planar gate is described, wherein the IGBT exhibits a shielding electrode in a groove, which shielding electrode is isolated from a gate electrode and connected to a source terminal. Furthermore, this IGBT has an n-region in the upper part of a drift region with a higher doping concentration than that of the drift region. The unit has one source region 140 and one gate at one side of the source region. A p+ contact region 142 is placed at the other side of the unit. The drawbacks of this structure are a small channel width per area and a slightly non-uniform arrangement of MOS channels.